The present invention relates to a direct current (DC) electrical power supply system. More specifically, the present invention relates to a modular power distribution system having a low profile and enhanced accessibility for maintenance and expansion.
Numerous operations, such as operation of telecommunication systems, require low voltage direct current (DC) electrical power supply systems for operating DC-powered equipment at remote sites or in central office installations. Such equipment often operate at low voltage, such as plus 24 volt to minus 48 volt DC power. Many of such operations, however, do not have DC power directly available and must convert conventional single-phase alternating current (AC) electrical power to DC power.
Traditional central office power supply systems typically require a height in excess of seven feet to accommodate the DC power supply system and related bus work and cabling. The traditional central office power supply systems typically have large overhead cables and buses above the DC power supply system to provide electrical connections among the various components of the system. Such overhead cabling and buses often result in excessive height requirements which limit expansion of the power supply system, makes installation and maintenance of the bus work complicated and costly. The height requirements for the overhead cabling and buses also often limit the location of the power system to those locations that can accommodate the height requirements.
Traditional power systems are also somewhat limited in expansion capability. Traditional systems are often expandable in one direction, for instance left or right. The direction of desired expansion, however, may be constrained by the location particulars. The locations containing traditional power systems are also usually not particularly spacious. In this regard it is also desirable to be able to install, service and modify such power supply systems in such a way that system installation, servicing and replacement of components may be carried out in an efficient manner. Such traditional systems often only have rear access for maintenance resulting in large space requirements for access at the rear of the systems while still requiring access in the from of the systems for routine operation and monitoring. Furthermore, maintenance or expansion typically requires the moving of a system assembly or cabinet in more space-limited enclosures lacking adequate maintenance access.
Thus, there is a need for a DC power supply system having improved capability for expansion and enhanced accessibility for maintenance and expansion. In particular, there is a need for a DC power system having access from the front portion of the system without having to move the system assembly or cabinet within the enclosure.
The present invention provides an improved DC electrical power supply system, particularly adapted for use in conjunction with equipment requiring reliable supply of low voltage DC power. The DC electrical power system of the present invention provides full access from the front portion of the system without having to move the system assembly. Shunts are positioned within the system so as not to limit the capability for expansion. Moreover, the bus design is integrated within the system while still not exceeding seven feet in overall height.
In one aspect of the present invention a modular power system for converting alternating current to direct current up to about 15,000 amperes or less is provided. The modular power system includes, in part, a modular power bay for converting alternating current to direct current and a modular power distribution assembly for distributing the direct current. The modular power bay includes a plurality of rectifiers for converting the alternating current to direct current, a power bay charge bus in electrical communication with the rectifiers for receiving the direct current therefrom and a frame for containing the rectifiers and the power bay charge bus. The modular power distribution assembly includes, in part, a plurality of electrical fuses or circuit breakers for routing direct current therethrough, a power distribution discharge bus in electrical communication with the fuses or circuit breakers and a frame for containing the fuses or circuit breakers and the power distribution charge bus.
The power bays of adjacent power bays and power distribution assemblies interconnect to provide electrical connection therethrough. The power bays are also contained within frames. The frames for the power bays and for the power distribution assemblies are typically no more than seven feet in height, which is a substantial reduction in height requirements for systems with similar power ratings.
The power system of the present invention may include a plurality of power bays with each power bay containing up to eight rectifiers with each rectifier being rated for up to 450 amperes of direct current. The power bays are electrically connected in series and adjacent power bays are interconnected at their charge and ground return buses.
The power system of the present invention further includes a shunt within the frame of the power distribution assembly for monitoring the amount of direct current entering the power distribution assembly. The shunt is electrically connected between the power distribution charge bus and the power distribution discharge bus which in turn is electrically connected the fuses or circuit breakers. The shunt is located within the power distribution assembly. The power system may contain a plurality of power distribution assemblies with each assembly having a shunt so that capacity of the system is not limited by a master shunt as additional assemblies are added to the system for expansion thereof.
In another aspect of the present invention a central DC office power system is provided for delivering direct current being up to about 15,000 amperes or less. The central DC office power system includes, in part, a modular power bay comprising a plurality of rectifiers for converting the alternating current to the direct current, a modular power distribution assembly comprising a plurality of electrical fuses or circuit breakers for routing direct current therethrough, a battery reserve for delivering supplemental DC current and a distribution fuse bay for delivering a plurality of DC currents to DC power-consuming equipment.
In yet another aspect of the preset invention, a power distribution assembly capable of receiving and delivering up to about 15,000 amperes or less of direct current is provided. The assembly includes, in part, a generally rectangular frame, a plurality of fuses or circuit breaker contained within the frame, a plurality of cables having fuse or circuit breaker-connecting ends connected to the fuse outlets, and a tray for supporting portions of the electrical cables at the fuse or circuit breaker-connecting ends. The fuse or circuit breaker outlets and the cable trays terminate near the front portion of the frame and are also angled towards the front portion of the frame to permit accessibility thereat. The frame has an opening or openings for access to the fuse or circuit breaker outlets and cable connections. The openings may be covered by a movable door and provide access to the fuse or circuit breakers, the fuse or circuit breaker outlets and the fuse or circuit breaker-connecting cable ends.